The producing technology of polymer Li-ion batteries was firstly disclosed by Bellcore, and the producing procedure includes preparation and assembly of positive electrode slice and negative electrode slice, and preparation of polymer electrolyte film. The process of preparation comprises the following steps: coating a punched aluminum foil and copper foil with positive electrode and negative electrode slurries, then inserting a polymer film or a gel electrolyte between the positive electrode and the negative electrode to isolate the positive electrode from the negative electrode; and after cutting positive electrode and negative electrode films, laminating and hot-pressing them to obtain battery cells. This process contains some troublesome steps, the cells obtained have bad uniformity and the rate of finished products is low. And as a result of the large thicknesses of the electrodes, the utilization rate of the electrode materials is low and the production cost is high.
Chinese Patent Application No. 200810060861.3, filed by Wanxiang Group Company, describes a process for preparing a polymer lithium battery substrate by a single-layer coating method using blade coating, but the coating thickness thereof is not specified. Chinese Patent Application No. 200810060860.9 describes a process for preparing a electrode coating by using spray coating, in which the coating uniformity of said process is, however, relatively low, and it is hard to control the thickness. Chinese Patent No. 00817741.4, owned by Sanyo Electric Corporation Ltd., describes a method for producing a battery current collector by a thin film deposition process, in which said collector can be made into an alloy with Li, and the alloy electrode has a good electrical conductivity. However, the deposition process needs a thermal treatment at a high temperature and the operating procedures are complicated and unfeasible for industrial production. Chinese Patent No. 200510002144.1, owned by BYD Company Ltd., introduces a method of preparing a electrode coating of lithium battery, which comprises steps of slurrying, rolling, slitting and cutting, but the patent does not describe any specific coating process and coating thickness. Chinese Patent Application No. 200580027720.6, filed by Japanese Central Research Institute of Electric Power Industry, introduces a method of producing a positive electrode slice for organic electrolyte lithium battery, but it does not indicate which coating preparation technology is applied.
According to the present invention, a method of preparing a new gel polymer Li-ion battery electrode coating by a multi-layer one-step coating technology is used, in which a positive electrode active material slurry, a gel polymer electrolyte slurry and a negative electrode active material slurry of the battery are coated with a high speed coater by a three-layer one-step coating technology to directly obtain a battery electrode coating of a two-layer composite structure of electrode active material/gel electrolyte or a three-layer composite structure of electrode active material/gel electrolyte/electrode active material. The method is originally creative and has never been reported in relevant patents and references.